When using a freshly installed Debian, users willing to connect to a proxy to surf the net (commonly used by professionals in a business environment) are confronted by two concerns related both to one thing: the @ sign is interpreted by the terminal as as a separator and not as part of the login or password. Some companies make use of logins in the following format "firstname.lastname@example.org" and it is therefore important for the system to consider the @ sign as part of the login. If your password contains an @, the sign will be interpreted as a separator and your password will be truncated.
Here are the solutions:
In all cases, the command lines must be entered in the terminal:
If you have permission errors, switch to root
In the case of a normal proxy where authentication can be done with a short name (for example, domain\user)
the syntax is: